brainpopfandomcom-20200223-history
Wildfires/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby (owl hoots) Tim is toasting marshmallows over a campfire in the woods. TIM: Moby, check it out. My new marshmallow technique is unstoppable. Moby, dressed like a forest ranger, shovels a pile of dirt onto the marshmallows and campfire. TIM: Why? MOBY: Beep. TIM: We're allowed to have a fire for cooking. The fire danger level is green. A sign shows the fire danger levels. Today it is green, the lowest level. The other levels are blue for moderate, orange for high, and red for extreme. MOBY: Beep. TIM: You know you're not an actual ranger, right? Tim reads from a typed letter. TIM: Dear Tim and Moby, I live in California and we're not allowed to build campfires. Can you explain why? From, Kate. Good question, Kate. I'm guessing your fire danger level is not green. Blue and green mean there's not much chance a campfire will get out of control; but as it moves closer to red, the slightest spark can trigger a wildfire. That's any fire that gets loose and spreads in nature. Moby turns the dial on the sign from green to blue, then to orange and red as Tim explains the danger levels. Then an animation shows two kids sitting around a campfire. A spark flies out of the campfire and starts a fire on the ground. TIM: Depending on what's burning, they might be called forest fires, brush fires, prairie fires, or something else. The animation shows how the brush fire spreads across the ground and up the trees. MOBY: Beep. TIM: They can burn at more than 2,000 degrees and eat up huge areas of land in a matter of days. The animation shows the trees on fire and smoke filling the air. TIM: Flying embers make them spread even faster. Every year, wildfires consume millions of acres. An animation shows a wildfire covering a huge forest area. TIM: They destroy homes and businesses, and put millions of people in danger. Side by side images show a burned-out house and a row of cars driving away from a wildfire. MOBY: Beep. TIM: To see how they catch and spread, we need to get into some chemistry. Fire is the visible energy thrown off by combustion. That's a chemical reaction between oxygen and a source of fuel. An animation shows a fire. Pop-up images show oxygen, a plus sign, and fuel. TIM: The fuel can be paper, dead leaves, plastic, trees; anything that burns. Images show the fuel examples Tim lists. TIM: And the oxygen comes from the air all around us. MOBY: Beep. Moby's thought bubble shows him reading a book that catches on fire. TIM: No. Lucky for us, oxygen doesn't combine with fuel on its own. Moby's thought bubble bursts. TIM: The reaction needs a third ingredient to get going: heat. Oxygen and fuel appear, followed by heat. The fuel catches on fire. TIM: If enough heat is added to the fuel, combustion will begin. Oxygen, fuel, and heat are shown as the three corners of a triangle. In the middle, a match lights. TIM: The energy it throws off will heat up nearby fuel, causing it to combust. This chain reaction is why fire spreads on its own. An animation shows the lit match. A close-up image shows that fuel and oxygen combine and combust from the heat, setting off a chain reaction. TIM: And the drier the fuel, the more easily it burns. An animation shows that fire applied to a dried out branch with no leaves spreads faster than fire applied to a branch with leaves. TIM: That's why more wildfires happen in dry climates, like out West and in Australia. During the hot summer months, these areas have all the ingredients for combustion. An animation shows a forest fire. Maps of the United States and Australia show the dry areas that are most susceptible to wildfires. MOBY: Beep? TIM: Sometimes, the sun itself provides enough heat to get the fire going. But it can also come from lightning, or lava. An animation shows an arrow pointing from the sun to dry brush in a forest. An image next to it shows lightning in a forest. TIM: Like droughts and floods, these kinds of wildfires are part of the earth's natural cycles. In fact, many ecosystems depend on them. MOBY: Beep? TIM: Mature forests and grasslands can be too crowded for new plants to thrive. An animation shows a forest that is crowded with vegetation. A fire startsand spreads. TIM: Wildfires consume old and dead material. They also clear away competitive species. An animation shows the forest on fire and deer running away from the flames. TIM: When they've passed, new growth begins to take hold. Animals return to their habitats, and the ecosystem rebounds, stronger than before. A clock sweeps by. The animation shows new growth in the forest, along with squirrels, butterflies, and birds. MOBY: Beep? TIM: Unfortunately, humans cause way more wildfires than the environment can handle. Loose cigarettes and unattended campfires are major culprits. So are downed power lines and even sparks from machinery. Images illustrate the causes of fires Tim describes. MOBY: Beep. Moby points straight ahead at the viewer. TIM: People do need to be a lot more careful. But it goes way beyond thoughtless mistakes. Too much fire suppression can also create dangerous conditions. In areas near cities, naturally occurring fires are put out before they can spread. An image shows a city right near a forest. TIM: Over time, a huge amount of fuel builds up. So when the fire does eventually happen, it's a whole lot worse. The image shows the flammable substances inside the forest. TIM: Climate change isn't helping the situation, either. MOBY: Beep. TIM: People add billions of tons of carbon to the atmosphere each year. Carbon traps heat, so average temperatures around the world are rising. An animation shows anindustrial plant emiting carbon into the earth's atmosphere. The carbon and heat from the sun, represented by an arrow, heat the atmosphere. TIM: That means more droughts, extended periods of dry weather. Which means more heat and dry fuel, two of the three ingredients needed for combustion. An animation shows a green forest turning brown and dry over time. MOBY: Beep? TIM: To fight fires, you have to remove one of those ingredients. Firefighters remove fuel by constructing a fireline. They dig a wide trench in front of where the fire is moving. It can't cross the trench if there's nothing to burn. Oxygen, fuel, and heat are shown as the three corners of a triangle. Inside the triangle, an animation shows firefighters digging a trench to create a fireline in a forest. When the trench is dug, the fuel symbol disappears. MOBY: Beep? TIM: It's not just a ground offensive. Water dropped from the air removes oxygen and heat. Chemicals that make the fire burn cooler can be mixed into the water. Oxygen, fuel, and heat are shown again in the three corners of a triangle. Inside the triangle, an animation shows planes dropping water and a red fire-fighting substance onto the fire. The symbols for heat and oxygen disappear. TIM: Big wildfires can take weeks to get under control. Once the flames are gone, the whole area is often cold trailed. Firefighters feel the ground with their bare hands, checking for heat. An image shows a forest after the wildfire is extinguished. Firefighters are shown feeling the ground with their hands. TIM: When the coast is clear, people who live nearby can return to their homes. MOBY: Beep. TIM: Right: If you live in an area prone to wildfires, be sure your family has an emergency plan. Tim and Moby are at a table with Tim's parents. Tim's mom is going down a checklist. TIM: Stock a kit with a flashlight, batteries, cash, and first aid supplies. The items Tim names are shown being placed into a container. TIM: If there's a wildfire nearby, stay tuned for weather updates and emergency instructions. An animation shows a boy viewing fire updates on a computer. TIM: And if you ever see a fire burning, call 911. The boy calls 911 when he looks out his window and sees a fire burning in the distance. MOBY: Beep. As Tim warms his hands over the campfire, Moby makes a phone call. TIM: I mean, if it's out of control. Are you gonna hang up? MOBY: Beep. TIM: Fine. Do what you want. Tim turns away from Moby. OPERATOR: 911. What's your emergency? Tim jumps on Moby and the phone falls to the ground. TIM: We're fine. Everything's fine! MOBY: Beep. OPERATOR: Hello? Hello?! Category:BrainPOP Transcripts Category:BrainPOP Science Transcripts